Ford: 1995 ford windstar, 1995 ford windstar, ford windstar

Question
Hello! Last week I bought a 95 Ford Windstar V6 3.8. (it had a jasper engine put in about 3 years ago, or so the car dealer says) I am hearing a strange rattling noise when the van is in drive and reverse. Kind of like a ping, or marbles in a tin can being shook around. It is rather loud at times. Also, the engine seems to have a deep humm to it. I dont think it is the muffler because the exhaust and stuff just passed inspection a few months ago. Also, when the van comes to a stop, it jerks a little bit. Maybe a bad mount of some kind? Are any of these things a sign of a serious or costly problem? Any advise will be appreciated. I dont have anyone else to ask.

Answer
a marble sound is usely a sign of a trans converter going bad is the trans sliping at all?also the noise could be the exhaust bracket by the trans is cracked and just needs to be welded this happens a lot.but to see it you have to look real close . good luck